STAINING BACTERIAL POLYSACCHARIDES

Abstract

Alcian Blue 8GN 150 was found to stain the bacterial capsules and insoluble polysaccharides in both pure and mixed cultures of bacteria and protozoa. This dye was found to be specific for any insoluble carbohydrate. At acid pH there was an affinity for acids as well as carbohydrates. The reaction was believed to be due to salt linkage in the case of the acids and to the internal hydroxyl group in the case of carbohydrates. The fact that bacterial protoplasm did not strain might be attributed to the complexity of the dye molecule preventing diffusion through the cell wall rather than the lack of affinity for the internal polysaccharides for the strain.